bims-metlip 2023-10-22 papers

bims-metlip

Biomed News

on Methods and protocols in metabolomics and lipidomics

Issue of 2023–10–22
28 papers selected by
Sofia Costa, Matterworks

Human Cerebrospinal Fluid Sample Preparation and Annotation for Integrated Lipidomics and Metabolomics Profiling Studies.
Microbial Metabolites Annotation by Mass Spectrometry-Based Metabolomics.
Advances in Mass Spectrometry-Metabolomics Based Approaches.
Matrix effect in bioanalytical assay development using supercritical fluid chromatography-mass spectrometry.
Mass spectrometry-based analysis of gut microbial metabolites of aromatic amino acids.
High throughput analysis of alendronate in human samples with derivatization-free hydrophilic-interactive chromatography mass spectrometry.
Analytical Strategy for Oxylipin Annotation by Combining Chemical Derivatization-Based Retention Index Algorithm and Feature Tandem Mass Spectrometric Fragmentation as a Biomarker Discovery Tool.
Rapid simultaneous determination of 7 fat-soluble vitamins in human serum by ultra high performance liquid chromatography tandem mass spectrometry.
Identification of variety-specific metabolites of basil by high performance thin layer chromatography-assisted metabolic profiling techniques.
Discovery of Modified Metabolites, Secondary Metabolites, and Xenobiotics by Structure-Oriented LC-MS/MS.
Optimising a urinary extraction method for non-targeted GC-MS metabolomics.
Non-Mass Spectrometric Targeted Single-Cell Metabolomics.
Sample Preparation in Microbial Metabolomics: Advances and Challenges.
Quantification and isotope abundance determination of 13C labeled intracellular sugar metabolites with hydrophilic interaction liquid chromatography.
Simultaneous determination of tramadol and paracetamol in human plasma using LC-MS/MS and application in bioequivalence study of -fixed-dose combination.
Untargeted metabolomics analysis on kidney tissues from mice reveals potential hypoxia biomarkers.
Determination of tobacco-specific nitrosamines in tobacco and mainstream cigarette smoke using one-step clean-up coupled with liquid chromatography- tandem mass spectrometry.
Simultaneous determination of three biomarkers of non-small cells lung cancer in urine by pipette-tip solid-phase extraction coupled with liquid chromatography tandem mass spectrometry.
Determination of restricted dyes in textile raw material solid wastes by ultra-high performance liquid chromatography-tandem mass spectrometry.
Study on the effect of calibration standards prepared with different matrix on the accuracy of bile acid quantification using LC-MS/MS.
Discovering New Natural Products Using Metabolomics-Based Approaches.
Improving LC-MS/MS measurements of steroids with differential mobility spectrometry.
Stereochemistry of aminoacylated cardiolipins and phosphatidylglycerols from bacteria.
Quantification of soluble epoxide hydrolase inhibitors in experimental and clinical samples using the nanobody-based ELISA.
A Comprehensive Comparison of Tissue Processing Methods for High-Quality MALDI Imaging of Lipids in Reconstructed Human Epidermis.
Implementation of charged microdroplet-based derivatization of bile acids on a cyclic ion mobility spectrometry-mass spectrometry platform.
Simultaneous determination and pharmacokinetics study of three triterpenoid saponins in rat plasma by ultra-high-performance liquid chromatography tandem mass-spectrometry after oral administration of Astragalus Membranaceus leaf extract.
Advances in Microbial NMR Metabolomics.

Mol Neurobiol. 2023 Oct 16.

Human Cerebrospinal Fluid Sample Preparation and Annotation for Integrated Lipidomics and Metabolomics Profiling Studies.

Kourosh Hooshmand, Jin Xu, Anja Hviid Simonsen, Asger Wretlind, Andressa de Zawadzki, Karolina Sulek, Steen Gregers Hasselbalch, Cristina Legido-Quigley.

  Cerebrospinal fluid (CSF) is a metabolically diverse biofluid and a key specimen for exploring biochemical changes in neurodegenerative diseases. Detecting lipid species in CSF using mass spectrometry (MS)-based techniques remains challenging because lipids are highly complex in structure, and their concentrations span over a broad dynamic range. This work aimed to develop a robust lipidomics and metabolomics method based on commonly used two-phase extraction systems from human CSF samples. Prioritizing lipid detection, biphasic extraction methods, Folch, Bligh and Dyer (B&D), Matyash, and acidified Folch and B&D (aFolch and aB&D) were compared using 150 μL of human CSF samples for the simultaneous extraction of lipids and metabolites with a wide range of polarity. Multiple chromatographical separation approaches, including reversed-phase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC), and gas chromatography (GC), were utilized to characterize human CSF metabolome. The aB&D method was found as the most reproducible technique (RSD < 15%) for lipid extraction. The aB&D and B&D yielded the highest peak intensities for targeted lipid internal standards and displayed superior extracting power for major endogenous lipid classes. A total of 674 unique metabolites with a wide polarity range were annotated in CSF using, combining RPLC-MS/MS lipidomics (n = 219), HILIC-MS/MS (n = 304), and GC-quadrupole time of flight (QTOF) MS (n = 151). Overall, our findings show that the aB&D extraction method provided suitable lipid coverage, reproducibility, and extraction efficiency for global lipidomics profiling of human CSF samples. In combination with RPLC-MS/MS lipidomics, complementary screening approaches enabled a comprehensive metabolite signature that can be employed in an array of clinical studies.

Keywords:  Cerebrospinal fluid; Lipidomics; Lipids; Mass spectrometry; Metabolomics

DOI:  https://doi.org/10.1007/s12035-023-03666-4
Adv Exp Med Biol. 2023 ;1439 225-248

Microbial Metabolites Annotation by Mass Spectrometry-Based Metabolomics.

Paulo Wender P Gomes, Talita Carla de Tralia Medeiros, Naydja Moralles Maimone, Tiago F Leão, Luiz Alberto Beraldo de Moraes, Anelize Bauermeister.

  Since the discovery of penicillin, microbial metabolites have been extensively investigated for drug discovery purposes. In the last decades, microbial derived compounds have gained increasing attention in different fields from pharmacognosy to industry and agriculture. Microbial metabolites in microbiomes present specific functions and can be associated with the maintenance of the natural ecosystems. These metabolites may exhibit a broad range of biological activities of great interest to human purposes. Samples from either microbial isolated cultures or microbiomes consist of complex mixtures of metabolites and their analysis are not a simple process. Mass spectrometry-based metabolomics encompass a set of analytical methods that have brought several improvements to the microbial natural products field. This analytical tool allows the comprehensively detection of metabolites, and therefore, the access of the chemical profile from those biological samples. These analyses generate thousands of mass spectra which is challenging to analyse. In this context, bioinformatic metabolomics tools have been successfully employed to accelerate and facilitate the investigation of specialized microbial metabolites. Herein, we describe metabolomics tools used to provide chemical information for the metabolites, and furthermore, we discuss how they can improve investigation of microbial cultures and interactions.

Keywords:  Bioinformatic; Metabolite annotation; Metabolomics

DOI:  https://doi.org/10.1007/978-3-031-41741-2_9
Adv Exp Med Biol. 2023 ;1439 101-122

Advances in Mass Spectrometry-Metabolomics Based Approaches.

Nerilson Marques Lima, Gabriel Franco Dos Santos, Gesiane da Silva Lima, Boniek Gontijo Vaz.

  Highly selective and sensitive analytical techniques are necessary for microbial metabolomics due to the complexity of the microbial sample matrix. Hence, mass spectrometry (MS) has been successfully applied in microbial metabolomics due to its high precision, versatility, sensitivity, and wide dynamic range. The different analytical tools using MS have been employed in microbial metabolomics investigations and can contribute to the discovery or accelerate the search for bioactive substances. The coupling with chromatographic and electrophoretic separation techniques has resulted in more efficient technologies for the analysis of microbial compounds occurring in trace levels. This book chapter describes the current advances in the application of mass spectrometry-based metabolomics in the search for new biologically active agents from microbial sources; the development of new approaches for in silico annotation of natural products; the different technologies employing mass spectrometry imaging to deliver more comprehensive analysis and elucidate the metabolome involved in ecological interactions as they enable visualization of the spatial dispersion of small molecules. We also describe other ambient ionization techniques applied to the fingerprint of microbial natural products and modern techniques such as ion mobility mass spectrometry used to microbial metabolomic analyses and the dereplication of natural microbial products through MS.

Keywords:  Ambient ionization techniques; Dereplication; Mass spectrometry; Mass spectrometry imaging; Microbial metabolomics

DOI:  https://doi.org/10.1007/978-3-031-41741-2_5
Biomed Chromatogr. 2023 Oct 16. e5759

Matrix effect in bioanalytical assay development using supercritical fluid chromatography-mass spectrometry.

Liuxi Chen, Yuxiang Cui, Brian Dean, Xiaorong Liang.

  Matrix effect (ME) is commonly caused by coelution of compounds with target analytes, resulting in either suppression or enhancement of analyte ionization. Thus, to achieve the desired accuracy, precision, and sensitivity, ME needs to be evaluated and controlled during bioanalytical method development. As the application of supercritical fluid chromatography-mass spectrometry (SFC-MS) for analysis of biological samples has increased, ME using SFC-MS has also been investigated with a focus on the difference in ME in SFC-MS compared to other chromatographic techniques used for achiral separation in biological samples. Here, we provide a summary of the status of ME evaluation and mitigation in SFC-MS methods. This review presents an overview of the phenomenon of ME and methods for evaluating ME in bioanalysis. Next, the factors that can impact ME in SFC-MS-based bioanalytical methods are discussed in detail with an emphasis on SFC. A literature review of the evaluation of ME in targeted bioanalytical methods using SFC-MS is included at the end. Robust instrumentation, effective sample preparation, and superb separation selectivity are the foundations of reliable analytical methods as well as the ability to mitigate detrimental ME in SFC-MS methods.

Keywords:  bioanalytical method validation; chromatographic techinique; ionization suppression/ionization enhancement; sample preparation

DOI:  https://doi.org/10.1002/bmc.5759
Comput Struct Biotechnol J. 2023 ;21 4777-4789

Mass spectrometry-based analysis of gut microbial metabolites of aromatic amino acids.

Narumol Jariyasopit, Sakda Khoomrung.

  Small molecules derived from gut microbiota have been increasingly investigated to better understand the functional roles of the human gut microbiome. Microbial metabolites of aromatic amino acids (AAA) have been linked to many diseases, such as metabolic disorders, chronic kidney diseases, inflammatory bowel disease, diabetes, and cancer. Important microbial AAA metabolites are often discovered via global metabolite profiling of biological specimens collected from humans or animal models. Subsequent metabolite identity confirmation and absolute quantification using targeted analysis enable comparisons across different studies, which can lead to the establishment of threshold concentrations of potential metabolite biomarkers. Owing to their excellent selectivity and sensitivity, hyphenated mass spectrometry (MS) techniques are often employed to identify and quantify AAA metabolites in various biological matrices. Here, we summarize the developments over the past five years in MS-based methodology for analyzing gut microbiota-derived AAA. Sample preparation, method validation, analytical performance, and statistical methods for correlation analysis are discussed, along with future perspectives.

Keywords:  Aromatic amino acid; Gut microbial metabolite; Mass spectrometry; Metabolomics; Quantitative analysis

DOI:  https://doi.org/10.1016/j.csbj.2023.09.032
J Pharm Biomed Anal. 2023 Oct 10. pii: S0731-7085(23)00544-7. [Epub ahead of print]237 115775

High throughput analysis of alendronate in human samples with derivatization-free hydrophilic-interactive chromatography mass spectrometry.

Yi-Fan Shieh, Fu-Mei Hung, Szu-Ning Yeh, Li-Ting Kao, Jen-Chi Chen, Fu-En Liao, Jenpang Huang, Chin-Hsiung Wang, Chi-Yang Lee, Jentaie Shiea.

  A derivatization-free hydrophilic-interactive chromatography-mass spectrometry (HILIC-MS/MS) method was developed for quantifying low levels of alendronate in human plasma. Alendronate was separated and concentrated using calcium co-precipitation and analyzed by HILIC-MS/MS, requiring only a 300 μL plasma sample for each analysis. The method is simpler, safer, and more environmentally friendly than the conventional LC-MS/MS method that requires solid-phase extraction and derivatization steps during sample pretreatment. The method was validated for selectivity, linearity, precision, accuracy, extraction recovery, matrix effect and limit of quantification. The between-run precisions were no more than 7.1 % with accuracy ranging from - 1.7-6.3 %; extraction recovery was determined to be 85.3 %; while validation results indicated that the method was suitable for accurately quantifying alendronate concentrations in the range from 0.2 to 50 ng/mL. The approach was used successfully for high throughput analysis of alendronate in more than 3700 plasma samples from 120 subjects in a bioequivalence study.

Keywords:  Alendronate; Bioequivalence; Bisphosphonate; Derivatization; Pharmacokinetics

DOI:  https://doi.org/10.1016/j.jpba.2023.115775
Anal Chem. 2023 Oct 18.

Analytical Strategy for Oxylipin Annotation by Combining Chemical Derivatization-Based Retention Index Algorithm and Feature Tandem Mass Spectrometric Fragmentation as a Biomarker Discovery Tool.

Zongyuan Wu, Huaming Xiao, Di Rao, Jie Wang, Xin Lv, Dan Wang, Ping Yao, Fenghong Huang, Hong Chen, Fang Wei.

Accurate oxylipin annotation is crucial for advancing our understanding of physiological processes in health and disease and identifying biomarkers. However, a full view of oxylipins for early diagnosis needs further attention due to the lack of proper analytical methods, which may be attributed to the wide dynamic range, poor sensitivity, extreme molecular complexity, and limited commercially available standards of oxylipins. Here, we devised a novel method by combining a chemical derivatization (CD)-based retention index (RI) algorithm and feature tandem mass spectrometric fragmentation annotation (CD-RI-LC-MS/MS) for identification and quantification of oxylipins. To this end, N,N-diethyl-1,3-diaminopropane (DEPA) was used for fast labeling of oxylipin (within 0.5 min at room temperature) to improve separation resolution and detection sensitivity. The RI algorithm was established to calibrate the retention time variances and assist the identification of oxylipins during liquid chromatography-tandem mass spectrometry (LC-MS) analysis. MS/MS analysis of in total 58 DEPA derivatives of authentic oxylipin standards was subsequently employed to obtain the tandem mass spectrometric feature fragmentation rules for further structure elucidation of the unknown regio-isomers. Finally, a method based upon CD-RI-LC-MS/MS was established for profiling oxylipins from Standard Reference Material (SRM) 1950 human plasma and nonalcoholic fatty liver disease (NAFLD) mouse liver tissue samples. A total of 87 and 96 potential oxylipins including 12 and 14 unreported oxylipins were detected and identified from human plasma and mouse liver tissues, respectively. The results showed that compared to the control group, in the liver samples of the NAFLD mouse, the content levels of prostaglandin (PG) E2, PGF2a, 8-hydroxy-eicosatrienoic acid (8-HETrE), and the newly discovered 2-hydroxy-octadecatrienoic acid (2-HOTrE) were remarkably increased, while the oxidation product of n-3 PUFA (p < 0.05) and all hydroperoxy oxylipins significantly decreased. On balance, this method contributes to future studies on oxylipin screening and application in other biological samples for facilitating the understanding of oxylipin roles in metabolic regulation of numerous diseases.

DOI: https://doi.org/10.1021/acs.analchem.3c02789
Anal Methods. 2023 Oct 17.

Rapid simultaneous determination of 7 fat-soluble vitamins in human serum by ultra high performance liquid chromatography tandem mass spectrometry.

Yumei Huo, Shangqing Zhang, Gaoping Wu, Hongbo Shan, Qianqian Li, Tongqing Deng, Chao Pan.

Accurate detection of vitamins is critically important for clinical diagnosis, metabolomics and epidemiological studies. However, the amounts of different vitamins vary dramatically in human serum. It is a challenge to achieve simultaneous detection of multiple vitamins rapidly. Herein, we developed and validated a sensitive and specific method using ultra high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for simultaneous quantification of 7 fat-soluble vitamins (FSVs) across their physiological concentrations in serum for the first time, which was subjected to protein precipitation, liquid-liquid extraction to an organic phase, evaporation to dryness and reconstitution with acetonitrile. In the present procedure, retinol (vitamin A), ergocalciferol (25-OH-D2), cholecalciferol (25-OH-D3), α-tocopherol (vitamin E), phylloquinone (vitamin K1), menatetrenone-4 (MK-4), and menaquinone-7 (MK-7) were detected in one analytical procedure for the first time within 5.0 min by triple quadrupole tandem mass spectrometry. The limit of quantification (LOQ) for vitamin A was 10.0 ng mL-1, LOQs for 25-OH-D2 and 25-OH-D3 were 1.0 ng mL-1, LOQ for vitamin E was 100.0 ng mL-1, and LOQs for vitamin K1, MK-4 and MK-7 were 0.10 ng mL-1, respectively, with a correlation (R2) of 0.995-0.999. Recoveries ranged from 80.5% to 118.5% and the intra-day and inter-day coefficients of variance (CVs) were 0.72-8.89% and 3.2-9.0% respectively. The method was validated according to the European Medicines Agency (EMA) and U.S. Food and Drug guidelines and C62-A on bioanalytical methods, and was used for clinical routine determination.

DOI: https://doi.org/10.1039/d3ay01527k
J Chromatogr A. 2023 Nov 08. pii: S0021-9673(23)00650-7. [Epub ahead of print]1710 464425

Identification of variety-specific metabolites of basil by high performance thin layer chromatography-assisted metabolic profiling techniques.

Windi Putri Wulandari, Yongran Ji, Özlem Erol, Young Hae Choi.

  The technological advances of analytical instrumentation and techniques has laid the ground for the rapid expansion of metabolomics or in a wider sense, untargeted analysis applied to life sciences themes. However, the objective of identifying all existing metabolites within organisms remains a daunting challenge. All analytical techniques exhibit varying degrees of sensitivity and versatility for the detection of metabolites and none of the existing analytical platforms can be expected to be ideal for exhaustive chemical profiling. Planar liquid chromatography, and in particular, high performance thin layer chromatography (HPTLC), has been used for chemical profiling of natural products in conjunction with metabolomics. HPTLC has specific advantages which include its ability to generate reliable chemical fingerprinting data and facilitate preparative work for metabolite isolation during later stages of metabolomics analysis. In this study, we investigated the chemical profiles of four commercially available basil cultivars, namely Dolly, Emily, Keira, and Rosie. We used HPTLC as the primary analytical tool for the separation of basil cultivars based on detected metabolites, and then compared the results with those obtained with other analytical platforms. We identified the characteristic marker compounds of each basil cultivar from the HPTLC plates and validated their potential using LC-MS and GC-MS analyses as a metabolomics tool. Firstly, we compared the HPTLC data of the four cultivars, obtained with two systems that used silica gel 60 and two mobile phases composed of toluene-EtOAc (8:2, v/v) and EtOAc-formic acid-acetic acid-water (100:11:11:27, v/v), with 1H NMR data to evaluate their separation power. Despite providing lower resolution and detecting fewer compounds, the HPTLC separation power was comparable, and in some cases even better than that of 1H NMR. Additionally, we investigated the potential of HPTLC as a tool for chemical fingerprinting and demonstrated its suitability for preparative purposes that are essential for identifying metabolites in mixture analysis. Metabolites were easily isolated from sample mixtures, and identified with the assistance of GC-MS, LC-MS, and TLC-densitometry.. Several marker compounds were thus identified, including 2,4 di-tertbutylphenol, palmitic acid, hexadecanamide, 9-octadecenamide, squalene, hentriacontane, methyl 3-(3,5-ditert‑butyl‑4-hydroxyphenyl)propanoic acid, sagerinic acid, and cyanidin-3-O-sophoroside.

Keywords:  Chemical profiling; HPTLC; Mass spectrometry; NMR; Ocimum basilicum

DOI:  https://doi.org/10.1016/j.chroma.2023.464425
Chem Res Toxicol. 2023 Oct 20.

Discovery of Modified Metabolites, Secondary Metabolites, and Xenobiotics by Structure-Oriented LC-MS/MS.

Kevin J Murray, Peter W Villalta, Timothy J Griffin, Silvia Balbo.

Exogenous compounds and metabolites derived from therapeutics, microbiota, or environmental exposures directly interact with endogenous metabolic pathways, influencing disease pathogenesis and modulating outcomes of clinical interventions. With few spectral library references, the identification of covalently modified biomolecules, secondary metabolites, and xenobiotics is a challenging task using global metabolomics profiling approaches. Numerous liquid chromatography-coupled mass spectrometry (LC-MS) small molecule analytical workflows have been developed to curate global profiling experiments for specific compound groups of interest. These workflows exploit shared structural moiety, functional groups, or elemental composition to discover novel and undescribed compounds through nontargeted small molecule discovery pipelines. This Review introduces the concept of structure-oriented LC-MS discovery methodology and aims to highlight common approaches employed for the detection and characterization of covalently modified biomolecules, secondary metabolites, and xenobiotics. These approaches represent a combination of instrument-dependent and computational techniques to rapidly curate global profiling experiments to detect putative ions of interest based on fragmentation patterns, predictable phase I or phase II metabolic transformations, or rare elemental composition. Application of these methods is explored for the detection and identification of novel and undescribed biomolecules relevant to the fields of toxicology, pharmacology, and drug discovery. Continued advances in these methods expand the capacity for selective compound discovery and characterization that promise remarkable insights into the molecular interactions of exogenous chemicals with host biochemical pathways.

DOI: https://doi.org/10.1021/acs.chemrestox.3c00209
Sci Rep. 2023 Oct 16. 13(1): 17591

Optimising a urinary extraction method for non-targeted GC-MS metabolomics.

Cara Olivier, Bianca Allen, Laneke Luies.

Urine is ideal for non-targeted metabolomics, providing valuable insights into normal and pathological cellular processes. Optimal extraction is critical since non-targeted metabolomics aims to analyse various compound classes. Here, we optimised a low-volume urine preparation procedure for non-targeted GC-MS. Five extraction methods (four organic acid [OA] extraction variations and a "direct analysis" [DA] approach) were assessed based on repeatability, metabolome coverage, and metabolite recovery. The DA method exhibited superior repeatability, and achieved the highest metabolome coverage, detecting 91 unique metabolites from multiple compound classes comparatively. Conversely, OA methods may not be suitable for all non-targeted metabolomics applications due to their bias toward a specific compound class. In accordance, the OA methods demonstrated limitations, with lower compound recovery and a higher percentage of undetected compounds. The DA method was further improved by incorporating an additional drying step between two-step derivatization but did not benefit from urease sample pre-treatment. Overall, this study establishes an improved low-volume urine preparation approach for future non-targeted urine metabolomics applications using GC-MS. Our findings contribute to advancing the field of metabolomics and enable efficient, comprehensive analysis of urinary metabolites, which could facilitate more accurate disease diagnosis or biomarker discovery.

DOI: https://doi.org/10.1038/s41598-023-44690-7
Trends Analyt Chem. 2023 Nov;pii: 117300. [Epub ahead of print]168

Non-Mass Spectrometric Targeted Single-Cell Metabolomics.

Hanjun Cheng, Yin Tang, Zhonghan Li, Zhili Guo, James R Heath, Min Xue, Wei Wei.

  Metabolic assays serve as pivotal tools in biomedical research, offering keen insights into cellular physiological and pathological states. While mass spectrometry (MS)-based metabolomics remains the gold standard for comprehensive, multiplexed analyses of cellular metabolites, innovative technologies are now emerging for the targeted, quantitative scrutiny of metabolites and metabolic pathways at the single-cell level. In this review, we elucidate an array of these advanced methodologies, spanning synthetic and surface chemistry techniques, imaging-based methods, and electrochemical approaches. We summarize the rationale, design principles, and practical applications for each method, and underscore the synergistic benefits of integrating single-cell metabolomics (scMet) with other single-cell omics technologies. Concluding, we identify prevailing challenges in the targeted scMet arena and offer a forward-looking commentary on future avenues and opportunities in this rapidly evolving field.

Keywords:  Raman microscopy; Single-cell metabolism; fluorescent metabolic tracer; microfluidic chip; single-cell amperometry; surface chemistry

DOI:  https://doi.org/10.1016/j.trac.2023.117300
Adv Exp Med Biol. 2023 ;1439 149-183

Sample Preparation in Microbial Metabolomics: Advances and Challenges.

Heiter V M Boness, Hanna C de Sá, Emile K P Dos Santos, Gisele A B Canuto.

  Microbial metabolomics has gained significant interest as it reflects the physiological state of microorganisms. Due to the great variability of biological organisms, in terms of physicochemical characteristics and variable range of concentration of metabolites, the choice of sample preparation methods is a crucial step in the metabolomics workflow and will reflect on the quality and reliability of the results generated. The procedures applied to the preparation of microbial samples will vary according to the type of microorganism studied, the metabolomics approach (untargeted or targeted), and the analytical platform of choice. This chapter aims to provide an overview of the sample preparation workflow for microbial metabolomics, highlighting the pre-analytical factors associated with cultivation, harvesting, metabolic quenching, and extraction. Discussions focus on obtaining intracellular and extracellular metabolites. Finally, we introduced advanced sample preparation methods based on automated systems.

Keywords:  Cellular cultivation; Extracellular metabolome; Intracellular metabolome; Metabolic quenching; Metabolite extraction; Microbial metabolomics; Sample preparation

DOI:  https://doi.org/10.1007/978-3-031-41741-2_7
Anal Methods. 2023 Oct 19.

Quantification and isotope abundance determination of 13C labeled intracellular sugar metabolites with hydrophilic interaction liquid chromatography.

Yameng Zhao, Ruoning Fan, Chuyao Wang, Sen Xu, Long Xie, Jinghua Hou, Wen Lei, Jianjun Liu.

Metabolic flux analysis (MFA) using stable isotope labeled tracers is a powerful tool to estimate fluxes through metabolic pathways. It finds applications in studying metabolic changes in diseases, regulation of cellular energetics, and novel strategies for metabolic engineering. Accurate and precise quantification of the concentration of metabolites and their labeling states is critical for correct MFA results. Utilizing an ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) system, an analytical method for simultaneously quantifying the concentration of sugar metabolites and their mass isotopologue distribution (MID) was developed. The method performs with good linearity and coefficient of determination (R2) > 0.99, while the detection limit ranged from 0.1 to 50 mg L-1. Seven sugar metabolites were detected in a labeled Brevibacterium flavum sample using the method. The detected quantities ranged from 6.15 to 3704.21 mg L-1, and 13C abundance was between 12.77% and 66.67% in the fermentation fluid and 16.28% and 91.93% in the bacterial body. Overall, the method is efficient, accurate, and suitable for analysis of labeled sugar metabolites in 13C MFA studies.

DOI: https://doi.org/10.1039/d3ay01178j
Ann Med. 2023 ;55(2): 2270502

Simultaneous determination of tramadol and paracetamol in human plasma using LC-MS/MS and application in bioequivalence study of -fixed-dose combination.

Gabriel Onn Kit Loh, Emily Yii Ling Wong, Chen Zhu Goh, Yvonne Tze Fung Tan, Yi Lin Lee, Lai Hui Pang, Siti Halimah Shahridzo, Nair Damenthi, Andi Hermansyah, Chiau Ming Long, Kok Khiang Peh.

  The study aimed to develop a sensitive and high-throughput liquid chromatography coupled with tandem mass spectrometry method to quantify concentrations of tramadol and paracetamol simultaneously in human plasma. Sample preparation involved single-step protein precipitation using methanol and two deuterated internal standards, tramadol D6 and paracetamol D4. Agilent Poroshell 120 EC-C18 (100 × 2.1 mm, 2.1 µm) analytical column was employed to achieve chromatographic separation. Detection was in positive ion multiple reaction monitoring mode. A tailing factor (Tf) of <1.2, separation factor (K prime) of >1.5 from the column dead time and signal-to-noise (S/N) ratio >10, were obtained for analytes and internal standards. The standard curve was linear over the concentration range of 2.5-500.00 ng/mL for tramadol and 0.025-20.00 μg/mL for paracetamol. A small injection volume of 1 µL, low flow rate of 440 µL/min and short analysis time of 3.5 min reduced the solvent consumption, analysis cost and system contamination. The results of method validation parameters fulfilled the acceptance criteria of bioanalytical guidelines. The method was successfully applied to a bioequivalence study of fixed-dose combination products of tramadol and paracetamol in Malaysian healthy subjects.

Keywords:  LC-ESI-MS/MS method; Tramadol; bioequivalence study; fixed-dose combination; paracetamol

DOI:  https://doi.org/10.1080/07853890.2023.2270502
Sci Rep. 2023 Oct 16. 13(1): 17516

Untargeted metabolomics analysis on kidney tissues from mice reveals potential hypoxia biomarkers.

Muhammad Imran Sajid, Francisco J Nunez, Farideh Amirrad, Moom Rahman Roosan, Tom Vojtko, Scott McCulloch, Amal Alachkar, Surya M Nauli.

Chronic hypoxia may have a huge impact on the cardiovascular and renal systems. Advancements in microscopy, metabolomics, and bioinformatics provide opportunities to identify new biomarkers. In this study, we aimed at elucidating the metabolic alterations in kidney tissues induced by chronic hypoxia using untargeted metabolomic analyses. Reverse phase ultrahigh performance liquid chromatography-mass spectroscopy/mass spectroscopy (RP-UPLC-MS/MS) and hydrophilic interaction liquid chromatography (HILIC)-UPLC-MS/MS methods with positive and negative ion mode electrospray ionization were used for metabolic profiling. The metabolomic profiling revealed an increase in metabolites related to carnitine synthesis and purine metabolism. Additionally, there was a notable increase in bilirubin. Heme, N-acetyl-L-aspartic acid, thyroxine, and 3-beta-Hydroxy-5-cholestenoate were found to be significantly downregulated. 3-beta-Hydroxy-5-cholestenoate was downregulated more significantly in male than female kidneys. Trichome Staining also showed remarkable kidney fibrosis in mice subjected to chronic hypoxia. Our study offers potential intracellular metabolite signatures for hypoxic kidneys.

DOI: https://doi.org/10.1038/s41598-023-44629-y
J Chromatogr A. 2023 Nov 08. pii: S0021-9673(23)00661-1. [Epub ahead of print]1710 464436

Determination of tobacco-specific nitrosamines in tobacco and mainstream cigarette smoke using one-step clean-up coupled with liquid chromatography- tandem mass spectrometry.

Yong Li, Tao Pang, Junli Shi, Xingyu Liu, Zhaoli Xu, Zhongbang Song, He Xie.

  A method for determining tobacco-specific nitrosamines (TSNAs) in tobacco and cigarette smoke using liquid chromatography-tandem mass spectrometry was established. The established method amended the deficiencies that exist in current mainstream methods. In this method, TSNAs in tobacco and cigarette smoke were extracted by water. The aqueous extract was then extracted by dichloromethane, and the extract could be analyzed by liquid chromatography-tandem mass spectrometry after a solvent replacement. This method was used to analyze flue-cured tobacco samples, and the response of the target compounds was about 10 times higher than that of the ammonium acetate extraction method. When analyzing cigarette smoke samples, the response strength and chromatographic peak purity of the target compounds were also significantly improved. The proposed method exhibited good linearities for both tobacco and cigarette smoke samples (r2 > 0.99). The limits of detection (LODs) for tobacco and cigarette smoke samples were 0.2-1.0 ng/g and 0.1-0.3 ng/cigarette, respectively. Additionally, this method exhibited desirable accuracy and precision. The TSNAs recovery values from tobacco and cigarette smoke samples ranged from 95.7 % to 107.7 % with inter- and intra-day relative standard deviations (RSDs) of less than 7.4 %. This method is simple, effective, and has wide adaptability. It is a useful upgrade to the existing methods for analyzing TSNAs in tobacco and cigarette smoke.

Keywords:  Cigarette smoke; Liquid chromatography-tandem mass spectrometry; Liquid-liquid extraction; Tobacco; Tobacco-specific nitrosamines

DOI:  https://doi.org/10.1016/j.chroma.2023.464436
J Chromatogr A. 2023 Oct 12. pii: S0021-9673(23)00673-8. [Epub ahead of print]1711 464448

Simultaneous determination of three biomarkers of non-small cells lung cancer in urine by pipette-tip solid-phase extraction coupled with liquid chromatography tandem mass spectrometry.

Wenyan Wang, Xiaohan Liu, Pengfei Zhang, Mingyu Wang, Yehong Han, Hongyuan Yan.

  Simultaneous determination of multiple biomarkers can improve the effectiveness and accuracy of cancer diagnosis. Cortisol, cortisone, and 4-methoxyphenylacetic acid (4-Me) are metabolic biomarker group with high specificity and sensitivity for the diagnosis of non-small cells lung cancer (NSCLC), and the development of their simultaneous determination method is desired. Herein, a simple, sensitive, and low-cost method involving pipette-tip solid-phase extraction (PT-SPE) using anion exchange adsorbent (MAX) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of three biomarkers (cortisol, cortisone, and 4-Me) in human urine. The sample (0.1 mL), adsorbent (1.5 mg) and organic reagent (3.5 mL) of MAX-PT-SPE are less consumed, and have the advantages of easy access to raw materials, simple assembly, convenient on-site instant extraction, low pollution, and low cost. The limits of detection of the three biomarkers were 0.006-0.024 ng mL-1, the recoveries of three spiked levels (2, 50, and 500 ng mL-1) were 91.0%-99.3%, with the relative standard deviations (RSDs) ≤ 5.9%. Finally, the MAX-PT-SPE-LC-MS/MS method achieved the quantitative analysis of cortisol, cortisone, and 4-Me in urine of different patients of NSCLC. This method is expected to be used in the non-invasive auxiliary diagnosis of NSCLC, and it provides a new strategy for multi-molecular diagnosis and multi-omics combined diagnosis.

Keywords:  Biomarker; Liquid chromatography-tandem mass spectrometry; MAX adsorbent; Pipette-tip solid-phase extraction

DOI:  https://doi.org/10.1016/j.chroma.2023.464448
J Chromatogr A. 2023 Oct 12. pii: S0021-9673(23)00672-6. [Epub ahead of print]1711 464447

Determination of restricted dyes in textile raw material solid wastes by ultra-high performance liquid chromatography-tandem mass spectrometry.

Qianran Sun, Yongli Li, Youzhi Su, Mengyuan Wei, Haitao Li, Jun Liu.

  A rapid and highly sensitive method for the quantification of 34 restricted dyes (including acid, basic, disperse, direct, and azo dyes) in solid textile raw material wastes was developed by employing ultrasonic extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS). More specifically, the proposed method employed methanol as the extraction solvent, while the mobile phases consisted of acetonitrile and 10 mmol/L ammonium acetate + 0.05% ammonia. A good linearity was achieved over the concentration range of 0.01-200 ng/mL with correlation coefficients (R) between 0.991-0.999, limits of detection (LODs) of 0.25-40.0 µg/kg (S/N = 3) and limits of quantification (LOQs) of 0.84-133.4 µg/kg (S/N = 10). 34 dyes were recovered at three levels ranging from 84.5 to 106.9% with relative standard deviation (RSDs) ranging from 0.59% to 10.61%. Further, the method was applied for the accurate analysis of 32 counts of cotton yarn, waste cotton, and printed fabrics within 15 min. The dyestuffs accurately quantified by this rapid chromatographic procedure covered a wide range of carcinogenic and allergenic dyestuffs listed in the Oeko-Tex Standard 100 (version 02.2023) colourants. The ultrasound technique combined with the ultra-high performance liquid chromatography-tandem mass spectrometry method proposed in this work is thus suitable for the rapid screening, confirmation, and quantitative detection of industrial synthetic dyes within solid waste originating from textile raw materials.

Keywords:  Restricted dyes; Textile raw material solids waste; UHPLC-MS/MS; Ultrasonic extraction

DOI:  https://doi.org/10.1016/j.chroma.2023.464447
J Pharm Biomed Anal. 2023 Oct 10. pii: S0731-7085(23)00554-X. [Epub ahead of print]237 115785

Study on the effect of calibration standards prepared with different matrix on the accuracy of bile acid quantification using LC-MS/MS.

Jinni Yang, Jiachun Lin, Anhui Wang, Xue Yang, Yali Wang, Yuting Zhang, Haijuan Dong, Yuan Tian, Zunjian Zhang, Min Wang, Rui Song.

  The transition from relative to absolute quantification of metabolites is the future development trend of mass spectrometry-based metabolomics research, which could fundamentally solve the problem of comparability of data between different laboratories. However, absolute quantification of endogenous molecules is largely hampered by the lack of analyte-free matrix, leading to uncertainty and inconsistency in the preparation of calibration standards. Bile acids (BAs) are an important class of biomarkers that play a key role in disease progression. In this paper, the quantitative accuracy of calibration curves prepared in neat solvent (NSCCs), charcoal stripped matrix (SMCCs) and authentic matrix (AMCCs) were validated using quality control samples (QCs) prepared in authentic matrix. Results suggested that AMCCs could largely minimize the confidence interval (C.I.) and the deviation in accuracy compared with NSCCs and SMCCs when measured concentration is higher than 20% of the background level. In addition, experimental data demonstrated that two-step calibration strategy proposed here is a promising and reliable alternative strategy to quantify endogenous BAs in biological sample.

Keywords:  Accuracy; Authentic matrix; Bile acids; Calibration standards; Surrogate matrix

DOI:  https://doi.org/10.1016/j.jpba.2023.115785
Adv Exp Med Biol. 2023 ;1439 185-224

Discovering New Natural Products Using Metabolomics-Based Approaches.

Lívia Soman de Medeiros, Moysés B de Araújo Júnior, Eldrinei G Peres, José Carlos Ipuchima da Silva, Milena Costa Bassicheto, Giordanno Di Gioia, Thiago André Moura Veiga, Hector Henrique Ferreira Koolen.

  The incessant search for new natural molecules with biological activities has forced researchers in the field of chemistry of natural products to seek different approaches for their prospection studies. In particular, researchers around the world are turning to approaches in metabolomics to avoid high rates of re-isolation of certain compounds, something recurrent in this branch of science. Thanks to the development of new technologies in the analytical instrumentation of spectroscopic and spectrometric techniques, as well as the advance in the computational processing modes of the results, metabolomics has been gaining more and more space in studies that involve the prospection of natural products. Thus, this chapter summarizes the precepts and good practices in the metabolomics of microbial natural products using mass spectrometry and nuclear magnetic resonance spectroscopy, and also summarizes several examples where this approach has been applied in the discovery of bioactive molecules.

Keywords:  Annotation; Data analysis; Dereplication; LC-MS; Metabolomics; Microbial metabolites; NMR; Natural products discovery

DOI:  https://doi.org/10.1007/978-3-031-41741-2_8
J Mass Spectrom Adv Clin Lab. 2023 Nov;30 30-37

Improving LC-MS/MS measurements of steroids with differential mobility spectrometry.

Yubo Chai, Stefan K G Grebe, Anthony Maus.

   Introduction: Steroid measurements are important for diagnosis and monitoring of many conditions and treatment regiments; however, due to structural and chemical similarities amongst steroids, these analyses are challenging, even for highly specific techniques such as liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differential mobility spectrometry (DMS) has the potential to improve these analyses by providing an orthogonal and complementary separation technique.
Methods: Initially, the potential for DMS to improve signal-to-noise ratio (S/N) and reduce interference was tested by comparing chromatograms acquired with and without DMS when performing measurements of six different steroids. Subsequently, a full clinical validation of cortisol and cortisone in urine was performed with the LC-DMS-MS/MS method.
Results and Discussion: DMS significantly reduced interferences observed in the chromatograms and boosted S/N by between 1.6 and 13.8 times. Additionally, DMS improved the agreement between quantifier/qualifier fragment ion results for cortisol and cortisone as indicated by the increase in R2 from approximately 0.81 to 0.98. All validation studies met acceptance criteria and we observed exceptional analytical performance in terms of precision, with % CVs less than 8%.
Conclusions: DMS improved the specificity of the steroid measurements by reducing interferences and improving S/N. The validation studies prove that these benefits did not come at the expense of other aspects of analytical performance. This study indicates that DMS has the potential to benefit not just clinical measurements of challenging analytes, but many clinical LC-MS/MS analyses.

Keywords:  Differential mobility spectrometry; Ion mobility; LC-MS/MS; Steroids; Tandem mass spectrometry

DOI:  https://doi.org/10.1016/j.jmsacl.2023.10.001
Electrophoresis. 2023 Oct 20.

Stereochemistry of aminoacylated cardiolipins and phosphatidylglycerols from bacteria.

Lucie Kyselová, Tomáš Řezanka.

  Hydrophilic interaction liquid chromatography (HILIC) connected with electrospray high-resolution tandem mass spectrometry (MS) was used for the analysis of unusual amino acid (AA) substituted phosphatidylglycerols (PG) and cardiolipins (CL) in mesophilic and thermophilic bacteria. Individual peaks from the lipid class separation by HILIC were isolated and hydrolyzed to determine the absolute configuration of the aminoacyl side chain. The configuration of the aminoacyl side chain was assigned by indirect liquid chromatography (LC) enantiomer separation after the hydrolysis of the aminoacylated (aminoacyl) lipids using N-(4-nitrophenoxycarbonyl)-l-phenylalanine 2-methoxyethyl ester as chiral derivatizing agent and reversed phase LC-MS for analysis. When two chromatographic methods were combined, less common AAs, such as d-allo-Ile and d-allo-Thr, were identified. The taxonomic classification of bacteria showed that bacteria of the family Bacillaceae (Bacillus and Geobacillus) produce branched-chain AAs, that is, d-allo-Ile, d-Ile, and d-Leu. These AAs were present only in the genera Bacillus and Geobacillus and not in Alicyclobacillus acidoterrestris (family Alicyclobacillaceae). On the contrary, hydroxy AAs, that is, l- and d-Thr, and l- and d-allo-Thr, were identified as aminoacyl-PG and aminoacyl-CL in A. acidoterrestris and were not present in the genera Bacillus and Geobacillus. Therefore, the complete analysis made it possible to identify the stereochemistry of AAs in aminoacyl PGs and CLs and use this fact for chemotaxonomy.

Keywords:  HILIC; achiral chromatography; amino acids; aminoacylated cardiolipins; aminoacylated phosphatidylglycerols

DOI:  https://doi.org/10.1002/elps.202300165
J Pharm Anal. 2023 Sep;13(9): 1013-1023

Quantification of soluble epoxide hydrolase inhibitors in experimental and clinical samples using the nanobody-based ELISA.

Huiyi Yang, Meng Qi, Qiyi He, Sung Hee Hwang, Jun Yang, Mark McCoy, Christophe Morisseau, Suqing Zhao, Bruce D Hammock.

  To ensure proper dosage of a drug, analytical quantification of it in biofluid is necessary. Liquid chromatography mass spectrometry (LC-MS) is the conventional method of choice as it permits accurate identification and quantification. However, it requires expensive instrumentation and is not appropriate for bedside use. Using soluble epoxide hydrolase (sEH) inhibitors (EC5026 and TPPU) as examples, we report development of a nanobody-based enzyme-linked immunosorbent assay (ELISA) for such small molecules and its use to accurately quantify the drug chemicals in human samples. Under optimized conditions, two nanobody-based ELISAs were successfully established for EC5026 and TPPU with low limits of detection of 0.085 ng/mL and 0.31 ng/mL, respectively, and two order of magnitude linear ranges with high precision and accuracy. The assay was designed to detect parent and two biologically active metabolites in the investigation of a new drug candidate EC5026. In addition, the ELISAs displayed excellent correlation with LC-MS analysis and evaluation of inhibitory potency. The results indicate that nanobody-based ELISA methods can efficiently analyze drug like compounds. These methods could be easily implemented by the bedside, in the field in remote areas or in veterinary practice. This work illustrates that nanobody based assays offer alternative and supplementary analytical tools to mass spectrometry for monitoring small molecule medicines during clinical development and therapy. Attributes of nanobody based pharmaceutical assays are discussed.

Keywords:  Immunoassay; Metabolites; Nanobody; Small molecules; Soluble epoxide hydrolase inhibitors

DOI:  https://doi.org/10.1016/j.jpha.2023.05.006
J Am Soc Mass Spectrom. 2023 Oct 16.

A Comprehensive Comparison of Tissue Processing Methods for High-Quality MALDI Imaging of Lipids in Reconstructed Human Epidermis.

Maureen Feucherolles, William Le, Jérôme Bour, Carine Jacques, Hélène Duplan, Gilles Frache.

  Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) has become an important tool for skin analysis, as it allows the simultaneous detection and localization of diverse molecular species within a sample. The use of in vivo and ex vivo human skin models is costly and presents ethical issues; therefore, reconstructed human epidermis (RHE) models, which mimic the upper part of native human skin, represent a suitable alternative to investigate adverse effects of chemicals applied to the skin. However, there are few publications investigating the feasibility of using MALDI MSI on RHE models. Therefore, the aim of this study was to investigate the effect of sample preparation techniques, i.e., substrate, sample thickness, washing, and matrix recrystallization, on the quality of MALDI MSI for lipids analysis of the SkinEthic RHE model. Images were generated using an atmospheric pressure MALDI source coupled to a high-resolution mass spectrometer with a pixel size of 5 μm. Masses detected in a defined region of interest were analyzed and annotated using the LipostarMSI platform. The results indicated that the combination of (1) coated metallic substrates, such as APTES-coated stainless-steel plates, (2) tissue sections of 6 μm thickness, and (3) aqueous washing before HCCA matrix spraying (without recrystallization), resulted in images with a significant signal intensity as well as numerous m/z values. This refined methodology using AP-MALDI coupled to a high-resolution mass spectrometer should improve the current sample preparation workflow to evaluate changes in skin composition after application of dermatocosmetics.

Keywords:  AP-MALDI; lipids; mass spectrometry imaging; reconstructed human epidermis; sample preparation; skin

DOI:  https://doi.org/10.1021/jasms.3c00185
Anal Methods. 2023 Oct 18.

Implementation of charged microdroplet-based derivatization of bile acids on a cyclic ion mobility spectrometry-mass spectrometry platform.

Olavs Rāciņš, Gabe Nagy.

Herein, we report the first implementation of charged microdroplet-based derivatization on a commercially-available cyclic ion mobility spectrometry-mass spectrometry platform. We have demonstrated the potential of our approach to improve separability of challenging isomers, but more importantly to rapidly screen derivatization reactions through droplet chemistry. Additionally, the use of cyclic ion mobility separations and tandem mass spectrometry reveals insights into product formation that would be lost with single stage mass spectrometry. Overall, we anticipate broad utility of our methodology owing to the simple design and setup for performing these droplet-based reactions and future work coupling these reactions online with liquid chromatography.

DOI: https://doi.org/10.1039/d3ay01447a
J Sep Sci. 2023 Oct 20. e2300282

Simultaneous determination and pharmacokinetics study of three triterpenoid saponins in rat plasma by ultra-high-performance liquid chromatography tandem mass-spectrometry after oral administration of Astragalus Membranaceus leaf extract.

Zhibin Wang, Gilwa Borjigin, Mingyu Zhang, Chunjuan Yang, Zhenyue Wang, Haixue Kuang.

  A selective and sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the determination of three triterpenoid saponins isolated from Astragalus membranaceus leaf extract. In this article, a method for simultaneous determination of Huangqiyenin A, Huangqiyenin E, and Huangqiyenin K was established for the first time. The method was successfully applied to the pharmacokinetic study of Astragalus membranaceus leaf extract after oral administration. Liquid-liquid extraction was applied to plasma sample preparation. Multiple reaction monitoring mode with an electrospray ion source in positive electrospray ionization was chosen to quantify the analytes. Chromatographic separation was performed on a Waters HSS T3 column, using gradient elution with a mobile phase composed of acetonitrile and 5 mM ammonium acetate/water. The pharmacokinetic results showed that all three compounds had the characteristics of rapid absorption-slow metabolism trend. The time of maximum plasma concentration of Huangqiyenin A is higher than Huangqiyenin E and Huangqiyenin K. And the maximum plasma concentration of Huangqiyenin A is higher as well. The pharmacokinetic results revealed the pharmacokinetic characteristics of the three analytes in rat plasma, which could provide a helpful reference for the further study of Astragalus membranaceus leaf extract.

Keywords:  astragalus membranaceus leaves; pharmacokinetics; rat plasma; triterpenoid saponins; ultra-high-performance liquid chromatography tandem mass-spectrometry

DOI:  https://doi.org/10.1002/jssc.202300282
Adv Exp Med Biol. 2023 ;1439 123-147

Advances in Microbial NMR Metabolomics.

Ricardo Moreira Borges, Gonçalo Jorge Gouveia, Fernanda Oliveira das Chagas.

  Confidently, nuclear magnetic resonance (NMR) is the most informative technique in analytical chemistry and its use as an analytical platform in metabolomics is well proven. This chapter aims to present NMR as a viable tool for microbial metabolomics discussing its fundamental aspects and applications in metabolomics using some chosen examples.

Keywords:  Microbial metabolomics; NMR

DOI:  https://doi.org/10.1007/978-3-031-41741-2_6